In multistage rotary machines used for energy conversion, such as a gas turbine engine, a hot working fluid is used to produce rotational motion. In a gas turbine engine, air is compressed in a compressor and mixed with a fuel in a combustor. The mixture of gas and fuel is then ignited to create a working gas comprising hot combustion gases that is directed to turbine stage(s) to produce rotational motion. Both the turbine stage(s) and the compressor have stationary or non-rotary components, such as vanes, for example, that cooperate with rotatable components, such as rotor blades, for example, for compressing and expanding the working gas. Many components within the machines must be cooled by cooling air to prevent the components from overheating.
Leakage of the working gas from a hot gas path to one or more disc cavities in the machines reduces performance and efficiency. Working gas leakage into the disc cavities yields higher disc and blade root temperatures and may result in reduced performance, reduced service life and/or failure of the components in and around the disc cavities.